Electric incandescent lamp

ABSTRACT

The invention relates to an electric incandescent lamp comprising a planar filament which is stretched in a frame construction of which a transverse support forms part which is resiliently movable relative to the longitudinal supports of the frame construction by means of two helical springs.

[ 1 Mar. 11,1975

limited States Patent v De Fraeye et a1.

Watrous..............

Randmcr m wm mam S mmm mwc SSP 7900 2677. 99999 4WUW i f 0 m 0 a b mun WW 3.5m fi W0 6 h D d .lmn m n .E e a R t m kmm .wwum DAE ms r 0 t n e v n l 1 ELECTRIC INCANDESCENT LAMP ABSTRACT Primary Examiner-Alfred E. Smith Assistant E.raminerSaxfield Chatmon, Jr. Attorney, Agent, or Firm-Frank R. Trifuri The invention relates to an electric incandescent lamp comprising a planar filament which is stretched in a frame construction of which a transverse support forms part which is resiliently movable relative to the longitudinal supports of the frame construction by means of two helical springs.

5 Claims, 3 Drawing Figures Netherlands [73] Assignee: U.S. Philips Corporation, New

York, NY

[22] Filed: Aug. 20, 1973 [21] Appl. No.: 390,169

[30] Foreign Application Priority Data Sept. 13 1972 Netherlands......................v

[52] US. 313/278, 313/273, 313/275 [51] Int. H0lj l/94, l-lOlj 19/48 [58] Field of Search 313/273, 276, 278, 274,

[56] References Cited UNITED STATES PATENTS 1583,463 5/1926 Houskcepcr....l............i.

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1 ELECTRIC INCANDESCENT LAMP The invention relates to an electric incandescent lamp comprising a frame construction in whicha filament is stretched, said frame construction being formed by two longitudinal supports and at least one transverse support manufactured from an insulating materialand secured to each of the longitudinal supports by means of a piece of wire wound around the longitudinal support, each longitudinal support projecting through one of the apertures present in the transverse support. Such an electric incandescent lamp is known.

In said known incandescent lamp, the filament is stretched between the two transverse supports or, when .only one transverse support is present, between said transverse support and an oppositely located part of the wall of the envelope of the incandescent lamp. The connection of the transverse support or transverse supports to the longitudinal supports is a rigid connection. During operation of the incandescent lamp it will be possible for the filament to sag due to expansion as a result of the increase in temperature. Furthermore, winding the piece of wire around the longitudinal support is a rather time-consuming operation, the more so since during said winding operation the filament is already present in the frame construction and should be maintained under the correct pre-stress.

It is the object of the invention to provide an electric incandescent lamp of the above-mentioned type which does not exhibit said drawbacks. For that purpose, the electric incandescent lamp according to the invention is characterized in that the piece of wire is formed as a helical spring which is locked with its one end in the aperture present in the transverse support and is secured with its other end to the longitudinal support.

By the spring action it is achieved that the adjusted stress in the filament is maintained during operation. Furthermore, the assembly of the frame construction is very simple: Actually each longitudinal support is threaded through the helical spring and the aperture in the transverse support after which the abovementioned other end of the helical spring is secured to the longitudinal support, for example, by a spot welding operation.

The connection of the helical spring to the transverse support is preferably carried out by embedding the helical spring in the material of the transverse support. This is particularly advantageous because due to the presence of the helical spring during the manufacture of the transverse support an aperture is formed in the material having the dimension required for receiving the longitudinal support.

A favourable embodiment of the electric incandescent lamp according to the invention is characterized in that a cylindrical body is embedded in each of the apertures in the transverse support, the diameter of said body being larger than the diameter of the helical spring secured in said body by means of a screwing operation. The walls of the aperture in the transverse support are formed by the cylindrical body. The transverse support is preferably formed from two beams of quartz glass which are softened and are then pressed against each other with their largest longitudinal dimension which clamping inbetween them the cylindrical bodies.

The invention will be described in detail with reference to the drawing, in which FIG. 1 shows an embodiment of an electric incandescent lamp according to the invention,

FIG. 2 is a cross-sectional view on an enlarged scale of the connections of the transverse support to the longitudinalsupport of the incandescent lamp taken on the linelI-II of FIG. 1 and FIG. 3 shows another embodiment of the connection of a transverse support to a longitudinal support.

The electric incandescent lamp which is shown in FIG. 1 and is destined for projection purposes comprises a lamp envelope 1 of a transparent material, for example quartz glass, from which two leadthrough conductors 2 and 3 project. A frame construction which is formed by two longitudinal supports 4 and 5 and two transverse supports 6 and 7 is arranged inside the lamp envelope 1. The longitudinal supports 4 and 5 which are formed from a refractory metal such as tungsten are connected to the lead-through conductors 2 and 3, respectively. The transverse supports 6 and 7 which are formed from quartz glass each comprise a number of hooks 8 which support the filament 9. The filament which is constructed from six parallel extending segments is welded to the longitudinal supports 4 and 5, respectively, with its ends 10 and 11, respectively.

The transverse support 7 in this embodiment comprises two recesses in which the longitudinal supports 4 and 5 are rigidly clamped. However, the connection of said transverse supports to the longitudinal supports may also be carried out differently, for example, while using a piece of wire.

For the connection of the transverse supports 6 to the longitudinal supports 4 and 5, the helical springs 12 and 13, respectively, are used. The ends 14 and 15, respectively, of said helical springs 12 and 13, respectively, are connected to the longitudinal supports 4 and 5, respectively, by a spot-welding operation. The oppositely located ends 16 and'l7, respectively, of the helical springs are locked in the transverse support 6 in a manner which will be explained in greater detail with reference to FIG. 2; the transverse support 6 is formed from two beams 18 and 19 of quartz glass which, after softening the quartz glass by heating, are pressed against each other with their largest longitudinal dimension while clamping inbetween them both the hooks 8 and two cylindrical members 20. The members 20 each consist of a helically wound piece of wire in which the ends 16 and 17 of the helical springs are screwed. When the two beams 18 and 19 of quartz glass which is still soft are pressed together, the pieces of wire are embedded as it were in the quartzglass while a cylindrical aperture is formed. The pieces of wire 20 have such a length that the transverse support 6 cannot tilt.

In the connection of a longitudinal support 21 to a transverse support 22 shown in FIG. 3, one end 23 of the spring is directly embedded in the material of the transverse support 22. Of course, the inner diameter of the helical spring should be chosen to be so wide that the longitudinal support can move axially relative to the transverse support and that in such manner that the transverse support 6 is moved in the direction away from the transverse support 7 when the filament 9 expands.

In the embodiment shown the helical springs 12 and 13 are formed as compression springs. It will be obvious, that the helical springs, when arranged on the side of the transverse support remote from the filament, should be constructed as expansion springs. In that case, the longitudinal conductors should of course extend over a certain distance beyond the relevant transverse support.

In the filament shown in FIG. 1 one side of the frame construction is formed by the transverse support 7. Of 5 and a coil spring fixed to said longitudinal support and disposed in coaxial relationship with at least an axial portion thereof engaging at least an axial portion of said coil spring in interspersed relation to prevent axial movement therebetween.

2. The apparatus as described in claim 1 wherein each of said coil springs extends axially between a first point fixed to said longitudinal support and said axial portion of said coil spring which engages said helix.

3. The apparatus as described in claim 1 wherein said coil spring is a compression spring.

4. The apparatus as described in claim 1 wherein said coil spring is a tension spring.

5. The apparatus as described in claim 1 wherein said transverse support comprises a glass member extending transverse to the axis of said helix and fused circumferentially to at least one axial section of said helix. 

1. An incandescent lamp comprising: two longitudinal supports disposed within said envelope, one transverse support, said transverse support being manufactured from an insulating material and carried on each of the longitudinal supports, a wire helix fixed to said transverse support and a coil spring fixed to said longitudinal support and disposed in coaxial relationship with at least an axial portion thereof engaging at least an axial portion of said coil spring in interspersed relation to prevent axial movement therebetween.
 1. An incandescent lamp comprising: two longitudinal supports disposed within said envelope, one transverse support, said transverse support being manufactured from an insulating material and carried on each of the longitudinal supports, a wire helix fixed to said transverse support and a coil spring fixed to said longitudinal support and disposed in coaxial relationship with at least an axial portion thereof engaging at least an axial portion of said coil spring in interspersed relation to prevent axial movement therebetween.
 2. The apparatus as described in claim 1 wherein each of said coil springs extends axially between a first point fixed to said longitudinal support and said axial portion of said coil spring which engages said helix.
 3. The apparatus as described in claim 1 wherein said coil spring is a compression spring.
 4. The apparatus as described in claim 1 wherein said coil spring is a tension spring. 